1. Field of the Invention
This invention relates to a finger grip collar designed to be placed on the proximal end of a syringe or cartridge barrel to facilitate the use of the same during the injection process.
2. Reported Developments
Syringes and cartridges made of glass or polymeric material for delivery of fluids to and from a patient have been proposed and utilized by the prior art, and have achieved a highly developed state. Various requirements related to specific delivery systems have also been addressed. While specific requirements of fluid delivery to and from a patient may vary, means of delivery remain essentially the same and may be characterized by the following general description of a syringe.
A syringe comprises:
a) a cylindrical barrel having a proximal end designed for receiving a plunger, with or without a plunger rod removably attached to the plunger or being integral with the plunger, and a distal end adapted to mount a needle or luer connector thereon; and PA0 b) a plunger slidably mounted in the barrel.
The plunger is inserted into the barrel at the proximal end of the syringe and thus, when fluid is contained in the barrel it may be expelled by pushing the plunger in the barrel towards its distal end; or when the syringe is used to withdraw fluid from a patient, the plunger located at the distal end of the barrel is pulled towards the proximal end of the syringe thereby drawing fluid into the barrel. Since a fluid-tight seal is necessary between the plunger and the inside wall of the barrel, a resilient rubber tip is positioned on the distal end of the plunger, or typically, the plunger is made of resilient rubber-like material. In some of the syringes of the prior art the rubber tip has been replaced with a generally flat, circular disk.
In order to assure air-tight seal between the inside wall of the syringe barrel and the plunger, prior art plungers are manufactured with a larger outside diameter than the inside diameter of the syringe barrels. When the plunger is introduced into the syringe barrel, it is sufficiently compressed to provide adequate pressure between the inside wall of the syringe and the plunger to seal the interface and withstand the challenges of filling, injecting and withdrawing fluids using the syringe without leakage.
In both the rubber and thermoplastic plungers a relatively large compressive force must be exerted on the plungers by the syringe barrel to provide for a tight, leak-proof seal. This quality of the seal, however, makes the movement of the plunger difficult. To remedy the problem the prior art used lubricants to reduce friction and drag between the plunger and the inside surface of the syringe barrel. The use of such lubricants, however, is also undesirable with certain parenteral fluids which tend to disperse or dissolve in the parenteral fluids thereby contaminating the parenteral fluids. Attempts to avoid the use of lubricants included the use of various plunger configurations, such as plungers that were provided with one or more ribs projecting fowardly or rearwardly in the barrel to reduce the frictional drag between the plunger and the inside surface of the barrel.
In using the syringe for injection to the patient or withdrawing fluid from the patient, the practitioner encounters two kinds of forces:
breakaway forces and running forces. The former relate to the forces at the start of the injection or withdrawal process necessary to move the plunger from its stationary position and the latter relates to the forces necessary to maintain the movement of the plunger at a steady rate of speed. Typically, the practitioner uses three fingers on one hand during the injection process to overcome/exert these forces: the thumb which exerts a force on the plunger rod and the index and middle fingers which hold the barrel of the syringe.
Recognizing the need to overcome the breakaway and running forces in a syringe, the prior art provided finger rests or finger-grip flanges on syringe barrels so that the practitioner could more securely and safely hold syringe barrel. Illustrative examples are U.S. Pat. Nos. 3,978,858; 5,115,816; 5,554,133; 5,573,514; 5,607,399; 5,697,918; and WO 97/11728.
It has been observed by practitioners that syringes equipped with finger rests or finger-grip flanges help in overcoming the breakaway and running forces during injections, however, practitioners would prefer to have a greater gripping surface so that control and accuracy of the amount of the fluid media delivered to the patient from the syringe would be more reliable.
It has also been observed that syringes equipped with finger rests or finger-grip flanges require specific orientation during the injection, i.e., the index and middle fingers should grip the finger rests or finger-grip flanges in order to achieve a secure holding of the syringe by the practitioner. This specific orientation is often missed especially under emergency situations.
With respect to glass syringes which typically are equipped with integral flanges of small gripping surface, the danger of breakage at the finger-grip flange exists during the injection process. Such breaking of the glass flange have been known to cause serious finger injuries to the practitioner. This hazard of injury is even more accentuated in the case of the so-called "flangeless" syringes where the proximal end of the barrel is constituted by a relatively narrow rim integral with the barrel.
I have now discovered that the above-mentioned shortcomings in syringes and cartridges may be overcome by an inexpensive snap-on finger-grip collar designed to accommodate various size barrels with or without integral finger rest or finger-grip flanges.